The invention relates to an excavation system using a grab guided near the area to be excavated.
Accurate guiding of the grab used in an excavating system becomes necessary when it is required to excavate the sea bottom and dump the spoil at a particular place. It is of course conventional to lower any system, tool well heads or the like to an exact spot, by vertical guiding using a number of lines secured between the seabed and a surface station. However, it has been found by experience that at least two cables close to one another are required for vertical guiding, very often with considerable risk of the lines becoming entangled. Automatic locating means are known but are highly complex and wholly unsuitable for controlling a grab.